The item I've seen most often drive a need for electrical service upgrade is a heat pump/airconditioner, or rather multiple units.

Actually, a larger service probably has a smaller consumption as the conductors are likely larger, but that's probably an imperceptible change in the bill.

400A service has kind of come and gone around here. Things have gotten more efficient so it's less of a problem. For example, given the high level of insulation in my house (spray foam), my A/C load (which is determining down here in NC) is much less. While I have 400A service I don't get anywhere near that.

Amusingly, the local power company keeps trying to sell me on an energy saving plan that allows them to cycle off my A/C at high demand times. I tell them it's going to be a neat trick (they mount the controller on the external compressor disconnect which I don't have on my Geothermal heat pumps).

It's amusing to watch the load monitoring (I've got a 80 KVA generator which is also rather oversized). I'm nowhere near peaking at the 200A service limits.

I thought about the conductor/resistance part. I dismissed it for a couple of reasons and I hope my logic was sound. Tell me if it is not. First, largest length of larger conductors is the drop or underground feed between the transformer and the home. The length of these are short compared to the conductors between the meter an the use point. The contribution is negligible. There are some homes that have a long way between the transformer and the home and maybe the OP has this situation. Second, the power loss in the drop or underground feed does not count because the meter is measuring power. In this light, the homeowner will save the power company some power by buying a larger service.

The growth of power consumption in residential sites grew for so long ,and the bias to making bigger when replacing equipment is so strong, that increasing service size is almost a knee-jerk reaction. Will we ever see the point when someone needs to replace a rusted-out 200A main panel and meter and says, or the electrician says, don't need 200A, you could probably get away with a 125, but lets oversize and go with 150? Recently, I arranged a service size increase in my dad's home. I did not want to. He had 125 A service going back decades, but I think the 1959 original was smaller. The nominal 200A combo main panel/transfer switch that I chose had two choices for main breakers, 200 and 150A. Darn it! That forced a complete main service replacement. On the positive side, adding the remaining stuff did not add much to the overall cost of genset instalation.

Ron, in your situation, if they are really bothersome, I'd be tempted to sign up for the energy savings program and then watch them scratch their heads after showing up. That kind of event might generate useful feedback to the sales part of the organization from their own field people (that is not getting trough from you). Once I got a call from a long distance telephone service provider asking me if I wanted to sign up. I thought for a second and said, go ahead. This was not too long after deregulation of that part of telephone service. At that moment, I was sitting at a university phone :-) The university had a system that went out and compared rates from two or three long distance services and put your call through the best way. I don't know what happened as a result of my saying yes to that caller. I am reasonably sure it is not what he expected. Was I being mean-spirited? I don't think so. I did benefit from a little amusement. I did not see my saying no and explaining likely being productive. If lucky, maybe I saved hundreds of other people on the university's exchange from nuisance calls and forced a productive change on their marketing end before they got too far into it.

Years ago, Virginia Power installed this gizmo on my hot water heater to do a similar thing. The community I was in was an "all electric" one at the time. They gave me $4 a month to have it. Amusingly, they appeared not to notice when we got gas finally run to the neighborhood and I put a gas stove, furnace, water heater, and even a gas dryer in (you think they'd notice the decrease in usage). One time I was down in the basement and noticed the thing blinking away indicating it was in conserve mode. Nice try, I said to myself.

Often with gas companies if usage drops precipitously, they install a new meter. I guess electric meters either work or don't work and failure modes don't include inaccuracy. I rented a home in Pittsburgh a long time ago. I was by myself there and kept the heat way, way, down even when I was home and I was not home much. Previously a small family was there. The gas co sent me notice that they had to install a new meter. I explained the scene, but they insisted on going ahead with their folly.

Ionized - many years ago gas company read the left most digit on the meter wrong. A $700 bill that took 3 months for them to correct. Fives years later they did the same thing and sent a $900 bill! I had to send them a photo of the meter and a copy of THEIR instructions on how to read a meter.

200 amp service is 48,000 watts 400 amp service is 96,000 watts (amperageXvoltage =wattage)

This does not mean that a residential grid meter is pulling those amperage amounts both have the capability to do so before tripping the main breaker or fuse from overload if properly designed. Determine what the onsite wattage load is and build the service to those numbers. Consider also that the more amperage being consumed the more heat that is being produced on the Main Breaker or Main Fuse until it reaches its limit and trips from over load. Motors, compressors and other large 240 volt amperage loads take more amperage at startup and if the Main is already maxed or nearly maxed than needless to say more heat is being generated than needs to be. Personally I design systems to peak at 80% of Main Breaker or Main Fuse rating leaving 20% in reserve for surges and start ups so that nothing will ever be starved or lag.

DB, my understanding is that breaker rating is for only 80% of the listed capacity continuous. Doesn't that mean that you must design at 80% max rating? Maybe you mean that you design for 64% of the listed capacity.

Personally I design systems to peak at 80% of Main Breaker or Main Fuse rating

I hope you don't mean that your"peak" value is the max that it is possible for the draw to be if every appliance was drawing it's full amount and every general circuit had devices plugged into it that were drawing the full amount.

ie. Add up all of the breakers in the panel and make the main breaker greater than that.

Because that is a huge waste and would result in an enormous oversizing of the service feed. Nobody is ever drawing anywhere near the max. A simple example is that AC units and heating units will never be used at the same time. A load calculation is much more complicated than that.

Other than the initial extra expense the 400 amp service is costing us, is there a downside to having the 400 amp service over the 200 amp service? Thanks for everyone's input!

Nope. Maybe it takes up more room if they're installing 2 panels, but that's it.

Should 400 amp services require electrical meter with multiplier?